The present invention relates to a method for adjusting phase to lessen a deviation of the phases of sounds generated from a plurality of speaker units; a sound reproducing apparatus to which the method for adjusting phase is applied; and a storage medium which records a program for implementing the method for adjusting phase by means of a computer provided with a feature serving as the sound reproducing apparatus.
In recent years, computers which are provided with a feature for reading out and reproducing image data and sound data recorded on a DVD (Digital Versatile Disk/Digital Video Disk) (hereinafter, simply referred to as a DVD feature) have been on the market. The sound data recorded on the sound track of the DVD is the data which is provided by compressing five channels of sound data having been subjected to signal processing to produce a sound effect which adds realism (surrounding effect) by encoding them using a coding scheme referred to as AC-3. In order to provide the surrounding effect when the sound is reproduced, as described in Published Unexamined Patent Application No. 4-318799 and No. 3-18200, it is required to dispose four, five, or more speakers around a listening position, and to cause each speaker to reproduce sound individually.
As the utilization of computers becomes more sophisticated and diversified, audio features, such as one for reproducing the sound data as an actual sound via speakers, are becoming indispensable features for computers (in particular, personal computers). In computers provided with the DVD function, in order to provide the surrounding effect when the DVD is replayed, they are designed to be equipped with an advanced audio feature which can reproduce a plurality of channels of sound data obtained by decoding the sound data read from the sound track of the DVD, as a sound of high quality via a plurality of speakers (for example, four speakers).
In contrast, since a typical computer is generally sold in a configuration including two speaker units for making the stereophonic reproduction of sounds possible, a user having a computer with the DVD function, and desiring to provide the surrounding effect when the DVD is replayed, has provided the surrounding effect when the DVD is replayed by additionally purchasing at least two speaker units (for example speaker units for disposal in the rear of the listening position), and connecting them to the computer to use them in combination with the speaker units included with the computer.
For reference sake, use of additional speaker units is not confined to the case where it is desired to provide the surrounding effect when the DVD is replayed. For example, some applications, such as game software being currently on the market in large quantity, may output four channels of sound data, and in the case where it is desired to reproduce more powerful sound when such an application is executed, additional speaker units may also be purchased and connected to the computer.
In commercially available speaker units which are sold for connection to computers, however, speaker units configured to generate sound 180xc2x0 out of phase with the sound signal input to the speaker units (sounds of opposite phases) (speaker units which are not in conformity with the JIS) are included. Since the phase relationship between the sound signal input to a speaker unit and the sound generated by the speaker unit is, as shown in FIG. 9 by way of example, varied due to various factors, such as whether the amplifier integrated into the speaker unit is a noninverting amplifier or an inverting amplifier, speaker units which generate sound of opposite phase to the sound signal input thereto are on the market in large quantity.
Therefore, the speaker units additionally purchased by a user may often be the speaker units which are configured to generate sounds of opposite phases as described above. In this case, there is a problem that the quality of the reproduced sound is significantly deteriorated because the sounds generated from the speaker units, for example, disposed in front of the listening position, and the sounds generated from the speaker units disposed in the rear of the listening position have opposite phases and cancel each other.
The present invention is provided in consideration of the facts described above, and an object of the present invention is to provide a method for adjusting phase, a sound reproducing unit, and a recording medium, which can avoid a significant deterioration of the quality of the reproduced sound regardless of the configurations of the speaker units used for reproducing sound.
In order to attain the object described above, in the method for adjusting phase according to the present invention, with a plurality of speaker units (two, four, or more) being respectively disposed at different positions for reproducing sound, a following procedure is performed for each of the plurality of speaker units, the procedure including inputting a predetermined reference sound signal to a single speaker unit, detecting a sound generated from the single speaker unit with sound detecting means disposed at a predetermined position for listening (for example, a position where a listener is situated at the time of listening sound), and detecting the phase difference between a sound signal output from the sound detecting means in response to the sound and the predetermined reference sound signal.
For example, where the number of speaker units is two, the speaker units may be situated at the right and left sides of the listening position, toward the front, and are substantially equidistant from the listening position. Where the number of speaker units is four, the positions where they may be disposed may comprise four positions which include the above-mentioned two positions, and two positions situated at the right and left sides of the listening position, toward the rear, and are substantially equidistant from the listening position. When the number of speaker units is five, the positions where they may be disposed comprise five positions which include the above-mentioned four positions, and a position situated at the center of the listening position, toward the front, and are substantially equidistant from the listening position.
The above-mentioned detection of the phase difference allows a phase difference between a sound signal input to a speaker unit and a sound generated by the speaker unit and listened at the listening position to be detected for each of a plurality of speaker units, and therefore, for example, even if a speaker unit configured to generate a sound of opposite phase to the sound signal input thereto is mixed in the plurality of speaker units, the significant difference between the detected phase difference values for this speaker unit and for the other speaker units allows the presence of the speaker unit of the above-mentioned configuration to be sensed.
Furthermore, in the method for adjusting phase according to the present invention, the phases of the sound signals which are input to each speaker unit when reproducing sound are altered relative to each other so that the deviation of the phase difference detected for each of the plurality of speaker units respectively is lessened. Changing the phases of the sound signals relative to each other may be accomplished by, for example, inverting the phases of the sound signals which are input to a particular speaker unit when reproducing sound, or changing the phases by a predetermined amount (for example, an amount corresponding to the deviation of the phase difference).
Thus, even if a speaker unit configured by generating a sound of opposite phase to the sound signal input thereto is mixed in a plurality of speaker units, the sounds individually generated by the plurality of speaker units when reproducing sound may be prevented from having phases that cancel each other at the listening position, so that a significant deterioration of the quality of the reproduced sound can be avoided regardless of the configurations of the speaker units used for reproducing sound.
Furthermore, the sound reproducing unit according to the present invention is provided with sound signal generating means that generates a plurality of channels of sound signals intended to be input to a plurality of speaker units respectively. Here, the sound reproducing unit according to the present invention may be a device having a function of reproducing sound via a plurality of speaker units, and as described below, it may be a computer or audio equipment. If the sound reproducing unit according to the present invention is a computer, some or all of the plurality of speaker units according to the present invention may be external speaker units connected to sound signal output terminals of the computer.
Furthermore, for the above-mentioned sound signal generating means, a configuration may be adopted that is designed, for example, to generate a plurality of channels of sound signals by reading data recorded on the sound track of the DVD, and decoding the read data. Here, it is also possible to adopt other configurations, including a configuration that is designed to acquire data by reading sound data from media other than DVD, such as a CD or the like, on which digital sound data is recorded, or by receiving sound data from other information processing devices via a communication line, and to convert the acquired sound data into sound signals to generate a plurality of channels of sound signals, or a configuration that is designed to read sound signal from media on which analog sound signal is recorded, such as an audio tape, to generate a plurality of channels of sound signals.
The sound reproducing unit according to the present invention is provided with means for detecting phase difference that, for each of a plurality of speaker units, inputs a predetermined reference sound signal to a single speaker unit of the plurality of speaker units, and detects phase difference between the predetermined reference sound signal and a sound signal output from the sound detecting means as a result of detecting a sound generated from the single speaker unit with sound detecting means disposed at a predetermined listening position, and phase adjusting means alters phase of a sound signal input to each speaker unit from the sound signal generating means relative to each other to lessen a deviation of the phase difference detected for each of the plurality of speaker units respectively. Therefore, as with the method for adjusting phase according to the present invention, a significant deterioration of the quality of the reproduced sound can be avoided regardless of the configurations of the speaker units used for reproducing sound.
Here, for the phase adjusting means, it is possible to adopt such a configuration that is designed to alter the phases of the sound signals relative to each other by inverting the phases of some of the sound signals according to the present invention input to each speaker unit. For example, if the sound signal generating means is configured to convert digital sound data into analog sound signal and input the analog sound signal to the speaker units to reproduce sound, the above-mentioned inversion of the phases of the sound signals may be accomplished very easily by inverting plus and minus the signs of the sound data. Furthermore, if the sound signal generating means is configured by directly generating sound signals without any conversion from sound data, etc., the inversion of the phases of the sound signals may be accomplished very easily by using an inverting amplifier, etc. Thus, it is possible to simplify the configuration of the phase adjusting means (that is, the configuration for lessening the deviation of the phase difference) by adopting, for the phase adjusting means, a configuration that is designed to alter the phases of the sound signals relative to each other by inverting the phases of the sound signals.
Furthermore, in the present invention, when phases of sound signals are to be altered relative to each other, the speaker unit for which the phase of the sound signal input thereto is altered may be selected arbitrarily from the plurality of speaker units, and if the plurality of speaker units comprises two or more speaker units disposed toward the front of the listening position, and two speaker units intended to provide surrounding effect disposed toward the rear of said listening position, the phase adjusting means may be configured, for example, to alter the phase of the sound signal input to one of the speaker units disposed toward the front of the listening position and speaker units disposed toward the rear of the listening position, to lessen a deviation of the phase difference between the phase difference detected for the speaker units disposed toward the rear of the listening position and phase difference detected for the speaker units disposed toward the front of the listening position.
If the sound reproducing unit according to the present invention is a computer, for a reason that additional speaker units are purchased, the manufacturer and configuration of the speaker units disposed toward the front of the listening position as described above are often different from those of the speaker units disposed toward the rear of the listening position, and thus the sound generated by the speaker units disposed toward the front of the listening position and the sound generated by the speaker units disposed toward the rear of the listening position often have opposite phases. However, on the contrary if the phase adjusting means is configured by altering the phase of the sound signal input to one of the speaker units disposed toward the front of the listening position and speaker units disposed toward the rear of the listening position, with a phase adjusting means having a simple configuration, it is possible to avoid a significant deterioration of the quality of the reproduced sound resulting from the fact that the sound generated by the speaker units disposed toward the front of the listening position and the sound generated by the speaker units disposed toward the rear of the listening position have opposite phases.
According to another aspect of the invention there is provided a recording medium intended to allow a computer to implement the method of adjusting phase comprising a first step of, for each of a plurality of speaker units, inputting a predetermined reference sound signal to a single speaker unit of the plurality of speaker units, and detecting phase difference between the predetermined reference sound signal and a sound signal obtained as a result of detecting a sound generated from the single speaker unit with a sound detecting means disposed at a predetermined listening position, and second step of altering phase of a sound signal input to each speaker unit relative to each other to lessen a deviation of the phase difference detected respectively for each of the plurality of speaker units, by reading out and executing the program recorded on the recording medium by the computer, as with the method for adjusting phase according to the present invention, a significant deterioration of the quality of the reproduced sound can be avoided regardless of the configurations of the speaker units used for reproducing sound.
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings.